White Grass?

hoping someone can help me here. i live in eastern mass and have a customer who's lawn in a couple sections is turning (white) on the top inch or so of each grass blade. one area is about 10x10, another area slightly smaller. it looks as if its spray paint drift but its not. i've asked her for info on anything she's done and she hasn't done anything. its also been like this since the begining of spring, about 10 weeks. it doesnt appear to be spreading right now either. in these two areas the lawn is thinner compared to the rest. thanks

Could have some areas of sod or seed which are susceptible to powdery mildew, fungus. Common problem in the shade. Kentucky bluegrass even new sod-quality varieties like Midnight are affected. Fine fescue and rye are not susceptible.